The HeatSnagger is a basic drain water heat recovery unit for a shower cabinet. The focus of the design has been a good price-performance ratio. Inside the HeatSnagger you find a 3 m copper pipe where the cold water to the shower mixer flows. It is a normal copper pipe bent in a meander shape with a 1/2″ fitting in each end. This pipe resides in a channel where some of the energy in the warm drain water is recovered when it preheats the cold water inside the copper pipe.
The first meter of copper pipe will have the highest heat recovery, adding another meter will still add to the efficiency, but not as much as the previous meter. Each added meter basically have the same cost in production, and we found the price-performance of a forth meter to be in the borderland of what pays off. So we made it just 3 m long.
The idea is to hook a good chunk of energy with a little effort. That´s why it is named The HeatSnagger.